Thorium (not lanthanum) has a half life comparable to the age of the
universe, so they'll be radioactive for quite a while yet.
Mark
On Fri, Nov 18, 2016 at 4:04 PM, Wayne Harridge <
wayne.harridge@xxxxxxxxxxxxxxxxxxx> wrote:
> What's the half-life of the active chemical elements in the lens ? Could
> be
> that those old 55/1.2 lenses are now radioactively "dead" by now.
>
> ...Wayne
>
>
> -----Original Message-----
> From: olympus
> [mailto:olympus-bounces+wayne.harridge=structuregraphs.com@
> thomasclausen.net
> ] On Behalf Of Ken Norton
> Sent: Saturday, 19 November 2016 3:39 AM
> To: Olympus Camera Discussion <olympus@xxxxxxxxxxxxxxxxx>
> Subject: Re: [OM] OM 55/1.2
>
> > Those with lanthanum glass (e.g. yellowing) are probably optically
> sharper/better than those without, since generally the lanthanum type glass
> was used because it had better optical properties (similar to how leaded
> glass is/was better, despite falling out of favor for various reasons).
>
>
> Like killing its owners?
>
> AG
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